Most container grown plants, particularly production grown pot plants, are watered from above by an arrangement which may include one or more of sprinklers, drippers, and a handheld hose. Increased costs of providing water and also attempts to better stabilise the water content of pots has led to growing interest in the use of bottom watering systems. Bottom watering has been widely practiced in the production of bedding plants, but its wider adoption will be highly likely to occur with other species as water costs escalate, water use is restricted and point source pollution is penalised.
It has been a long held ambition of plant propagators to maximise the effect of watering to thereby improve pot plant culture, not only to reduce water stress but also in terms of automation leading to lower labour requirements and increased efficiency.
The traditional pot plant is formed from a durable polymer or clay material and has a central drainage hole or a plurality of basal holes and/or holes arranged peripherally around a lower wall or base or centrally in the base. One major problem that arises with the use of such pots relates to water uptake and drainage of excess water through the holes, both of which processes are likely to become impeded by root growth. Roots may physically obstruct the passageway provided by the hole or holes. Roots may also concentrate within but at the base of the pot below the potting medium forcing the medium up and out of direct contact with a capillary watering bed in a commercial bottom watering system. This is highly likely to reduce upwards capillary flow rate since the capillary flow rate through a root mass will be compromised relative to the flow through the growth medium.
Escaped roots may also mat beneath a pot causing attenuation of the contact between the water delivery mat and plant-growing medium, thereby further compromising capillary supply of water to the plant.
A commonly promoted theory is that roots seek out a source of water and grow into the source of water to such an extent as to eventually plug the water conduit (see, for example, U.S. Pat. No. 5,938,372 to Lichfield). The teaching therefore is that roots will grow preferentially in the direction of incoming water and are positively hydrotropic.
It would be of advantage to provide a pot that limited root escape and also provided a pathway for liquid to move out of and preferably into the pot.